EP3836329B1 - Surge protector - Google Patents

Description

Technical area

The present description relates generally to devices for supplying, from a power source, a power supply to a load. The application relates more particularly to a power supply interface connected between a load to be powered and a USB-C type connector, the connector being intended to be electrically connected to a power source, in particular by a USB-C type cable.

Prior technique

Although today wireless is one of the major axes of research in the field of energy and data exchange, cables still seem to be the most reliable way to connect several electronic devices, whether either to exchange data or to power or recharge one or more electronic devices. The documents US 2014/021135 A1 And US 2014/0146426 A1 present electronic circuits for supplying power.

Among the different types of cables and connectors of the USB standard, the USB-C type is one of the types that allows the exchange of data and energy. USB-PD or USB "Power Delivery" technology is a technology that adapts to USB-C type cables and connectors. This technology allows power management of electronic devices. The document US 2018/0335454 A1 presents a device compatible with USB-PD technology.

Summary of the invention

It would be desirable to be able to improve at least in part certain aspects of the devices for supplying, from a power source, a power supply to a load by means of connectors and a cable if necessary. appropriate, in particular via USB-C connectors adapted to the technology USB-PD, and, if applicable, a USB-C cable suitable for USB-PD technology.

In particular, it would be desirable to be able to improve at least certain aspects of a power supply interface connected between a load to be powered and a connector, for example of the USB-C type, the connector being intended to be electrically connected to a power source. power supply, for example via a USB-C type cable.

One embodiment overcomes all or part of the drawbacks of known devices for supplying, from a power source, a power supply to a load.

One embodiment overcomes all or part of the drawbacks of known power supply interfaces connected between a load to be powered and a connector, for example of the USB-C type, the connector being intended to be electrically connected to a power source, by example by a USB-C type cable.

• un premier interrupteur reliant une borne d'entrée de l'interface à une borne de sortie de l'interface ;
• un pont diviseur de tension reliant la borne d'entrée à un noeud de référence configuré pour recevoir un potentiel de référence ;
• un comparateur dont une première entrée est connectée à un premier noeud du pont diviseur et dont une deuxième entrée est configurée pour recevoir un potentiel constant ;
• un convertisseur numérique analogique ;
• un deuxième interrupteur reliant une sortie du convertisseur à un deuxième noeud du pont diviseur ; et
• un premier circuit configuré pour commander le deuxième interrupteur et le convertisseur,
• dans lequel une commande du premier interrupteur est déterminée par un signal de sortie du comparateur.

One embodiment provides a power supply interface comprising:

• a first switch connecting an input terminal of the interface to an output terminal of the interface;
• a voltage divider bridge connecting the input terminal to a reference node configured to receive a reference potential;
• a comparator, a first input of which is connected to a first node of the divider bridge and a second input of which is configured to receive a constant potential;
• a digital-to-analog converter;
• a second switch connecting an output of the converter to a second node of the divider bridge; And
• a first circuit configured to control the second switch and the converter,
• wherein a command of the first switch is determined by an output signal of the comparator.

According to one embodiment, the divider bridge comprises at least one first resistor connecting the input terminal to the first node, at least one second resistor connecting the first node to the second node and at least one third resistor connecting the second node to the output node. reference.

According to one embodiment, the input terminal is configured to receive a first potential, the output terminal being configured to receive a second potential.

According to one embodiment, the interface is intended to receive the first potential from a power source, and to supply the second potential to a load.

According to one embodiment, the first circuit is also configured to negotiate a setpoint value of the first potential, and to control the converter according to the negotiated setpoint value.

According to one embodiment, the first circuit is configured to command closing of the second switch after the negotiation of said setpoint value.

According to one embodiment, the interface further comprises a second circuit configured to supply a control signal for the first switch from the output signal of the comparator.

According to one embodiment, the interface further comprises a third circuit, a first terminal of which is connected to the input terminal by the first switch, and a second terminal of which is connected to the output terminal, the third circuit being configured to supply, to the second terminal, a potential of the first terminal in a first mode of operation or a third potential in a second mode of operation.

According to one embodiment, the first circuit is configured to select an operating mode from among the first and second operating modes.

According to one embodiment, the third circuit comprises a power converter configured to supply the third potential from the potential of the first terminal.

According to one embodiment, the first switch is an MOS transistor.

According to one embodiment, the second switch is configured to be open in the absence of a command from the first circuit.

According to one embodiment, the second switch is a MOS transistor, preferably normally off.

According to one embodiment, the first circuit comprises, preferably consists of, a microcontroller.

• recevoir un premier potentiel de la source ;
• détecter avec un comparateur que le premier potentiel est inférieur à un seuil et conditionner une fermeture d'un premier interrupteur reliant la source à la charge à ladite détection ; et
• négocier, avec la source, une valeur de consigne du premier potentiel,
• dans lequel le seuil est fixe dans un premier mode de fonctionnement, et est déterminé par la valeur de consigne négociée dans un deuxième mode de fonctionnement, le procédé étant de préférence mis en oeuvre par une interface d'alimentation.

Another embodiment provides a method for powering a load from a power source comprising the following steps:

• receiving a first potential from the source;
• detecting with a comparator that the first potential is lower than a threshold and conditioning a closing of a first switch connecting the source to the load to said detection; And
• negotiate, with the source, a set value of the first potential,
• wherein the threshold is fixed in a first mode of operation, and is determined by the negotiated setpoint value in a second mode of operation, the method preferably being implemented by a power supply interface.

Brief description of the drawings

• la figure 1 est une vue schématique illustrant une connexion entre un dispositif électronique comprenant une source d'alimentation et un dispositif électronique comprenant une charge à alimenter ;
• la figure 2 représente, de manière plus détaillée, un mode de réalisation d'une partie du dispositif électronique de la figure 1 qui comprend la charge à alimenter ; et
• la figure 3 illustre par des courbes le fonctionnement de la partie du dispositif électronique de la figure 2, selon un exemple de mode de mise en oeuvre.

These characteristics and advantages, as well as others, will be set out in detail in the following description of particular embodiments given on a non-limiting basis in relation to the attached figures, among which:

• there figure 1 is a schematic view illustrating a connection between an electronic device comprising a power source and an electronic device comprising a load to be powered;
• there figure 2 shows, in more detail, an embodiment of a part of the electronic device of the figure 1 which includes the load to be powered; And
• there picture 3 illustrates by curves the operation of the part of the electronic device of the figure 2 , according to an exemplary embodiment.

Description of embodiments

The same elements have been designated by the same references in the different figures. In particular, the structural and/or functional elements common to the various embodiments may have the same references and may have identical structural, dimensional and material properties.

For the sake of clarity, only the steps and elements useful for understanding the embodiments described have been represented and are detailed. In particular, the management of a negotiation phase concerning the supply power to be supplied to a load from a supply source is not detailed. In addition, only relevant aspects of USB-C and USB-PD technologies are described, other aspects adapting without modifications. In particular, the data exchange function via connectors, and if necessary a USB-C type cable, preferably adapted to USB-PD technology, is not described, the embodiments described being compatible with the function of usual data exchange of USB-C and USB-PD technologies.

Unless otherwise specified, when reference is made to two elements connected together, this means directly connected without intermediate elements other than conductors, and when reference is made to two elements connected (in English "coupled") between them, this means that these two elements can be connected or be linked through one or more other elements.

In the following description, when referring to absolute position qualifiers, such as "front", "rear", "up", "down", "left", "right", etc., or relative, such as the terms "above", "below", "upper", "lower", etc., or to qualifiers of orientation, such as the terms "horizontal", "vertical", etc., it reference is made unless otherwise specified to the orientation of the figures.

Unless specified otherwise, the expressions “about”, “approximately”, “substantially”, and “of the order of” mean to within 10%, preferably within 5%.

There figure 1 is a schematic view illustrating a transmission of energy between an electronic device 200 having the role of a power source (SOURCE) and an electronic device to be powered 400 having the role of a load (SINK). In this example, the devices 200 and 400 are connected via a USB-C type C cable, in this example adapted to USB-PD technology. In another example not shown, devices 200 and 400 are directly connected to each other, without cable C.

The device 200 comprises an electrical power source 201. The power source 201 is for example a continuous power supply (DC), for example obtained from an AC power source such as the mains. In the rest of the description, it is considered that the device 200 comprises a DC power source 201, the device 200 being for example a computer, a portable battery, etc. or any other electronic device suitable for powering a device and/or recharging a battery.

Cable C comprises, at each of its ends, a connector C1, C2 of the USB-C type, in this example adapted to USB-PD technology. Connectors C1, C2 are generally identical.

A connection element 210, respectively 410, comprising a connection interface 214, respectively 414, and a connector 212, respectively 412, is arranged on the side of the device 200, respectively of the device 400. The interface 214, respectively 414, connects the source 201, respectively the load to be supplied (not shown) of the device 400, to the connector 212, respectively 412. Preferably, it is considered that the connection elements 210, respectively 410, form part of the device 200, respectively 400. Each connector 212 , 412 is configured to cooperate with a connector C1, C2 of the cable C. The interfaces 214, 414 are generally identical. The connection interfaces 214, 414 make it possible to adapt the supply power supplied by the supply source 201 according to the supply power required by the load of the device 400. More particularly, in the remainder of the description, the connection interfaces 214, 414 make it possible to adapt the power supply supplied by the power supply source 201 according to a power setpoint power supply requested by the device 400, in particular in the case where the USB-PD technology is implemented. In particular, the interface 214 on the side of the power source 201 generally comprises a power converter (not shown) configured to supply, from the power supply delivered by the source 201, the power supply that the device 200 supplies the device 400. Similarly, the interface 414 on the side of the load to be supplied generally comprises a power converter (not shown), for example configured to generate, from the supply power received by the device 400, a supply power which is actually supplied to the load to be powered of the device 400.

During a connection managed by USB-PD technology, an initial supply power, generally of a predefined value for example equal to 2.5 W, is supplied by the interface 214 of the device 200 to the interface 414 of the device 400. Once the interface 414 is powered by this initial power supply, communication is established between the devices 200 and 400, via their interfaces 214 and 414, to decide on the electric power supply necessary for the device 400 to able to be supplied and/or recharged. For example, the device 400 indicates, via its interface 414, the minimum power required for its operation and the device 200 indicates, for example via its interface 214, the power supplies that it is capable of supplying. A negotiation, in this example managed by USB-PD technology, then begins to define what power the device 200 will supply to the device 400. Once this negotiation is complete, the connection interface 214 adapts the power supply of the power source 201 in accordance to the result of the negotiation, then the powering of the device 400 begins.

By way of example, the negotiated power supply power is selected from a list of predefined power supplies. This list is for example recorded in the interface 214. Preferably, this list is defined by a standard. Each predefined supply power is characterized by several values, in particular by a predefined voltage value and, where appropriate, by a predefined maximum current value corresponding to this predefined power. In USB-PD technology, each set of values characterizing a predefined power supply from the list corresponds to a set of information designated by the acronym PDO (“Power Data Object”). These sets of PDO information can be transmitted between devices 200 and 400 adapted to USB-PD technology to define, during a negotiation, which of the predefined powers the device 200 must deliver to the load 400. In this example, the negotiated supply power received by interface 414 from device 400 may not be matched to the load to be powered from device 400, and the power converter of interface 414 may then be used to provide matched supply power to the load of device 400, from the negotiated supply power received by device 400.

By way of example, once a supply power has been negotiated, the supply voltage supplied by device 200 to interface 414 of device 400 may be slaved by the load of device 400 to match a supply voltage required by a load of the device 400, typically a battery to be recharged. This mode of operation is said to be at power supply Programmable Power Supply, or PPS mode. In this case, the interface 414 is, according to one embodiment, configured to directly supply the load of the device 400 with the supply power that it receives from the device 200, and in particular the supply voltage that it receives from device 200.

When devices 200 and 400 are connected and device 200 is providing supply power to device 400, it is desirable that the supply voltage that is supplied to interface 414 by device 200 not have a surge. Indeed, such overvoltages are likely to lead to malfunctions of the device 400, or even to damage the device 400, in particular its interface 414 or its load to be powered. In particular, when the load to be supplied is a battery to be recharged and the system operates in PPS mode, any overvoltages on the supply voltage received by the interface 414 are transmitted directly to the load to be supplied from the device 400, this which can lead to malfunctions, or even destruction, of the load of the device 400.

The inventors here propose a power supply interface 414, in which, during a connection between the devices 200 and 400, as long as the device 400 receives a predefined initial supply power, or, in other words, as long as a supply voltage has not been negotiated, the supply voltage received by the interface 414 is compared with a predefined fixed threshold so as to detect an overvoltage. In addition, once a setpoint supply power, and more particularly a setpoint supply voltage, has been negotiated, the interface is configured to compare the received supply voltage to a threshold determined by the voltage setpoint power supply negotiated, so as to detect an overvoltage. The inventors more particularly propose an interface 414 in which the same elements and/or circuits and/or components of the interface 414 are used to compare the supply voltage received with the fixed threshold in a first phase of operation, and with the variable threshold determined by a reference voltage negotiated in a second operating phase.

There picture 2 shows, in more detail, an embodiment of the interface 414 of the device 400 of the figure 1 . Preferably, interface 414 is of the USB-C type, for example adapted to USB-PD technology, interface 214 possibly being identical to interface 414.

Interface 414 comprises two input terminals 301 and 303. Terminal 301 is configured to receive a direct (DC) supply potential, for example positive, terminal 303 being intended to receive a reference potential, for example a ground potential GND. In other words, interface 414 is configured to receive a continuous supply voltage Valim, for example positive, between terminals 301 and 303.

The interface 414 comprises two output terminals 305 and 307. The terminal 305 is configured to supply a continuous supply potential Valim' to a load of the device 400, the terminal 307 supplying the reference potential GND and being for example connected to terminal 303. In other words, interface 414 is configured to supply, from voltage Valim, a continuous supply voltage Valim', for example positive, between terminals 305 and 307.

The interface 414 further comprises, on the side of its input terminals 301 and 303, at least one communication terminal. The input terminals 301 and 303 and communication are all intended to be connected to the corresponding connector 412 (not shown), which then allows the connection with the device 200, for example via the connector C2, the cable C if necessary and the connector C1 as shown in figure 1 .

According to one embodiment, the interface 414 comprises two communication terminals CC1, CC2 as shown in picture 2 . An advantage of having two communication terminals is that, in the case where these terminals are positioned symmetrically on the connector 412, this makes it possible to manufacture a reversible C2 connector, that is to say a C2 connector, for example rectangular in shape, which can be coupled to the connector 412 in a first direction and in a second direction opposite to the first.

The interface 414 comprises a switch 309, for example a MOS ("Metal Oxide Semiconductor" - metal oxide semiconductor) transistor, for example an N-channel MOS transistor. Preferably, the switch 309 is configured to be default, c that is to say in the absence of a command, in the open state, the switch 309 then being for example implemented by means of a normally off (“normally OFF”) MOS transistor.

The switch 309 connects the input terminal 301 to the output terminal 305. For example, a first conduction terminal of the switch 309 is connected, preferably connected, to the terminal 301, a second conduction terminal of the switch 309 being connected to terminal 305. By conduction terminal of a switch is meant here one of the two terminals of a switch between which a current flows when the switch is closed, and between which the switch behaves like an open circuit when the switch is open.

The interface 414 further comprises a resistive divider bridge 311. The divider bridge 311 connects the terminal 301 to the terminal 303. In other words, the divider bridge 311 connects the input terminal 301 to a node 313 configured to receive the reference potential GND, this node 313 being connected, preferably connected, to the terminal 303. For example, the bridge divider 311 comprises one end 315 connected, preferably connected, to terminal 301, and another end 317 connected, preferably connected, to node 313.

The divider bridge 311 comprises two nodes 319 and 321.

According to one embodiment, the divider bridge 311 comprises at least one resistor R1 connecting the end 315 of the bridge 311 to the node 319, at least one resistor R2 connecting the node 319 to the node 321, and at least one resistor R3 connecting the node 321 at the end 317 of the bridge 311. By way of example, the divider bridge 311 comprises a resistor R1, one terminal of which is connected, preferably connected, to the end 315 of the bridge 311 and the other terminal of which is connected , preferably connected, to node 319, a resistor R2, one terminal of which is connected, preferably connected, to node 319 and the other terminal of which is connected, preferably connected to node 321, and a resistor R3, one terminal of which is connected , preferably connected, to node 321 and whose other terminal is connected, preferably connected, to end 317 of bridge 311.

The interface 414 comprises a comparator 323. The switch 309 is controlled from an output signal comp_sig of the comparator 323.

According to one embodiment, the interface 414 comprises a close control circuit 325 ("driver circuit" in English), configured to supply, from the signal comp_sig, a control signal corresponding to a control terminal of the switch 309, for example a gate of an MOS transistor implementing switch 309.

A first input of comparator 323, in this example the inverting (-) input of comparator 323, is connected to node 319 of divider bridge 311. The first input of comparator 323 is configured to receive the potential of node 319 of divider bridge 311 A second input of comparator 323, in this example the non-inverting input (+), is configured to receive a constant or fixed potential Vth, for example referenced to ground GND.

According to one embodiment, the interface 414 comprises a diode 327, for example a Zener diode, preferably a band-gap Zener diode, connecting the second input of the comparator 323 to the node 313 The diode 327 is configured to supply the constant potential Vth to the second input of the comparator 323, this potential Vth preferably being constant despite possible variations in temperature in the interface 414. By way of example, the diode 327 has a first electrode, preferably its anode, connected, preferably connected, to the node 313, and a second electrode, preferably its cathode, connected, preferably connected, to the second input of the comparator 323. Alternatively, the potential Vth is supplied to the second input of comparator 323 by a circuit other than a diode 327.

The interface 414 comprises a digital-to-analog converter DAC and a switch 329, preferably a switch 329 configured to be in the open state by default. Switch 329 connects an output of the DAC converter to node 321 of divider bridge 311. For example, a conduction terminal of switch 329 is connected, preferably connected, to the output of the DAC converter, another conduction terminal of the switch 329 being connected, preferably connected, to the node 321. Thus, when the switch 329 is closed, the potential of the node 321 is imposed by a potential Vdac available on the output of the DAC converter, and, when switch 329 is open, the potential of node 321 is imposed by the value of potential Valim on terminal 301 and the values of resistors R1, R2 and R3 of divider bridge 311.

According to one embodiment, the switch 329 is an MOS transistor, for example N-channel, preferably a normally off MOS transistor.

The interface 414 comprises a circuit 331 (“CTRL” block) configured to control the switch 329. The control circuit 331 comprises an output 3311 connected, preferably connected, to a control terminal of the switch 329, for example a gate of a transistor implementing switch 329.

The control circuit 331 is further configured to control the DAC converter, that is to say to supply a digital control signal, for example on several bits, to an input of the DAC converter, the value of the digital control signal determining the value of the potential Vdac supplied by the output of the DAC converter. In the example represented, the DAC converter is external to the circuit 331, and the circuit 331 comprises an output 3312 configured to supply the control signal of the DAC converter, the output 3312 being linked, preferably connected, to the input of the converter DAC. In another example not shown, the DAC converter is part of circuit 331.

According to one embodiment, circuit 331 comprises or consists of a microcontroller. Preferably, the DAC converter is then an internal component of the microcontroller.

According to one embodiment, circuit 331 is configured to implement various functions of interface 414.

More particularly, according to one embodiment, the circuit 331 is configured to implement the data exchange functions with the device 200 ( figure 1 ), and comprises, in this example, two terminals respectively connected to the two terminals CC1 and CC2.

Furthermore, according to one embodiment, the circuit 331 is configured to implement, for example jointly with the interface 214 of the device 200 ( figure 1 ), the phase of negotiating a set power supply that device 200 will supply to device 400.

Preferably, interface 414 includes a circuit 333 connecting switch 309 to terminal 305 of interface 414. For example, circuit 333 includes a first terminal 3331 connected, preferably connected, to switch 309, and more particularly to the conduction terminal of switch 309 which is on the side of terminal 305 of interface 414, circuit 333 comprising a second terminal 3332 connected, preferably connected, to terminal 305.

The circuit 333 is configured to receive, for example on its terminal 3331, a first potential, for example the potential Valim, and to supply, for example on its terminal 3332, a second potential, for example the potential Valim'. The circuit 333 is for example connected, preferably connected, to the reference node 313.

According to one embodiment, in a first operating mode where the supply voltage Valim is equal to the supply voltage negotiated between the devices 200 and 400 ( figure 1 ) but has a value which is not adapted to the load of the device 400, the circuit 333 is configured to adapt the value of the second potential Valim' to the load. For this, the circuit 333 comprises for example a power converter (not shown). This first mode of operation is for example implemented when the power negotiated power supply is chosen from the predefined list of power supplies, and that the negotiated power supply corresponds to a set value of the potential Valim which is not adapted to the load of the device 400. In a second mode operating mode, for example the PPS mode, the circuit 333 is configured to supply the second potential at a value equal to that of the first potential which it receives, for example by connecting its terminal 3331 to its terminal 3332 as illustrated by dotted lines in picture 2 .

By way of example, circuit 331 is configured to control circuit 333, for example to provide circuit 333 with a signal controlling the selection of the operating mode of circuit 333 from among the first and second operating modes described above.

The operation of interface 414 is as follows.

When connecting device 200 to device 400, via connectors 212 and C1, cable C if applicable, and connectors C2 and 412 ( figure 1 ), the device 200 supplies an initial supply power, for example a voltage Valim with an initial value equal to 5.5 V, for example for an initial supply power equal to 2.5 W.

Switches 309 and 329 are open by default. Thus, even if the potential Valim has a value far from the initial value that it should have, the initial power received by the device 400 ( figure 1 ) is not passed on to him.

The potential Valim received is compared with a fixed (constant) high threshold, for example equal to 5.9 V. This fixed threshold is determined by the value of the potential Vth and of the resistors of the divider bridge 311. Indeed, the potential of the node 319 is then representative of the value of the potential Valim, and the comparator 323 then compares the potential of the node 319 with the potential Vth. More particularly, in this example, the potential of the node 319 is equal to (Valim*(R2+R3))/(R1+R2+R3) and is compared to the fixed potential Vth. In other words, the potential Valim is compared with a threshold equal to ((R1+R2+R3)*Vth)/(R2+R3).

If the potential Valim is lower than this high threshold, this means that the potential Valim does not present an overvoltage and the switch 309 is switched to the closed state. For example, the switch 309, and when present the circuit 325, are configured so that the switch is closed, respectively open, when the signal comp_sig is in a first binary state, for example the high state, respectively in a second binary state, for example the low state. The comparator 323 is then configured so that the signal comp_sig is in the first binary state, respectively the second binary state, when the potential Valim is lower than the high threshold, respectively higher than the high threshold, that is to say in this example when the potential of the node 319 is lower, respectively higher, than the fixed potential Vth.

Closing switch 309 causes terminal 301 to be connected to terminal 305, preferably via circuit 333.

Once the switch 309 is closed, the interface implements a phase of negotiation of a setpoint supply power, therefore of a setpoint value of the potential Valim. By way of example, the reception by the interface 414 of the initial supply power enables the supply of the circuit 331 which then implements this negotiation phase.

Furthermore, from the moment the switch 309 is switched to the closed state, any overvoltage on the potential Valim causing the potential Valim to exceed the fixed high threshold is detected by a switching of the signal comp_sig which causes the opening of the switch 309. This makes it possible to protect the components of the device 400 from this overvoltage ( figure 1 ) connected to terminals 305 and 307 of interface 414.

Once the supply power negotiation is completed between the devices 200 and 400, or in other words once a set value of the potential Valim is determined by the devices 200 and 400, the device 200 adapts the value of the potential Valim to the negotiated setpoint.

In addition, the high threshold with which the potential Valim is compared to detect a possible overvoltage is updated, the value of the high threshold then being determined by the setpoint value of the potential Valim. Indeed, the negotiated setpoint value of the potential Valim can be greater than that of the fixed threshold with which the potential Valim is compared during the first operating phase where the interface 414 receives the initial supply power and negotiates a supply power . The result would be that, in the absence of modification of the high threshold in accordance with the negotiated setpoint value of the potential Valim, the signal comp_sig would then switch to the binary state indicating that the potential Valim is greater than the fixed high threshold, which would cause the opening of the switch 309 and would stop the power supply of the load of the device 400.

The update of the high threshold is implemented, by closing the switch 329, from which it follows that the potential Vdac is forced, or applied, on the node 321 of the divider bridge 311, the value of the potential Vdac being determined by the negotiated set point value of the potential Valim. As a result, the potential of node 319 received by the first input of comparator 323 is then equal to ((Valim-Vdac)*R2)/(R1+R2)+Vdac. In other words, the high threshold to which the potential Valim is compared is then equal to ((Vth* (R1+R2)-R1*Vdac)/R2 and is indeed determined by the value of the potential Vdac, or, in other words, variable in function of the value of the potential Vdac. The value of the potential Vdac is determined by the digital control signal received by the input of the DAC converter, or, in other words, is determined by the circuit 331, the value of the digital control signal of the converter DAC being determined by the circuit 331 from the negotiated setpoint value of the potential Valim.

In particular, for a given negotiated setpoint value of the potential Valim, the potential Vdac is chosen so that the potential Valim is lower than the variable high threshold when its value is equal to the negotiated setpoint value, and is higher than the variable high threshold when the potential Valim presents an overvoltage. It will be noted that, for a given setpoint value of the potential Valim, the choice of the value of the potential Vdac, therefore of the amplitude of an increase in the value of the potential Valim with respect to its setpoint value from which one considers that an overvoltage is present on the potential Valim, is within the reach of those skilled in the art depending, for example, on the load to be powered of the device 400 and/or the application or the device in which is placed implements the 414 interface.

Thus, once a set value of the potential Valim has been negotiated, the potential Valim is compared with a variable high threshold to detect an overvoltage on the potential Valim and to command an opening of the switch 309 when such an overvoltage is detected.

Furthermore, each update of the setpoint value of the potential Valim leads to a corresponding update of the value of the high threshold with which the potential Valim is compared.

By way of example, the updating of the setpoint value of the potential Valim results from the implementation of a new phase of negotiation of a supply power.

As another example, while a power supply has been negotiated, when the interface 414, and more generally the devices 200 and 400 ( figure 1 ), operate in PPS mode, the potential setpoint value Valim is updated periodically or continuously, for example according to a measured value of the current flowing between terminals 301 and 305 and the setpoint value of the power supply negotiated. This makes it possible to maintain a set point value of the potential Valim adapted to the load of the device 400.

In the operation of the interface 414 described above, the threshold with which the potential Valim is compared is fixed (constant) in a first phase of operation, beginning for example with the connection of the devices 200 and 400 to each other and ending with example at the end of a first step of negotiation of a supply power, and is variable in a second phase of operation, starting for example at the end of the first step of negotiation.

In a variant embodiment, although this is not represented here, the closing of the switch 309 can also be conditioned by the result of a comparison of the potential Valim with a low threshold. In this case, the switch 309 is in the closed state only if the potential Valim is between the high and low thresholds, and is maintained in the open state otherwise. The low threshold can be fixed in the first and second phases of operation of the interface 414, or can be fixed in the first phase of operation and variable according to the set point value of the potential Valim in the second phase of interface operation. In the case where the low threshold is fixed in the first phase of operation of the interface 414, and variable in the second phase of operation of the interface 414, the implementation of the low threshold and the comparison of the potential Valim with the low threshold can be implemented in a manner similar to the implementation described above respectively of the high threshold and of the comparison of the potential Valim with the high threshold.

There picture 3 illustrates by curves 500, 502, 504, 506, 508, 510 the operation of the interface 414 according to one embodiment.

More particularly, in this implementation example, resistor R1 has a value equal to 100 kΩ, resistor R2 has a value equal to 6.2 kΩ, resistor R3 has a value equal to 21 kΩ and potential Vth is equal to 1.27 V. Furthermore, in this example, it is considered that the initial supply power corresponds to an initial value of the potential Valim equal to 5.5 V. Furthermore, in this example, the interface 414 puts implements a comparison of the potential Valim with a low threshold UVLO, here equal to 3.5 V.

Curve 500 corresponds to an increasing potential ramp Valim supplied to terminal 301. Curve 502 illustrates the corresponding shape of the potential supplied to terminal 3331 of circuit 333 in the event that switch 329 and the DAC converter are omitted, or, in other words, the case where the switch 329 would always remain open. Curves 504, 506, 508 and 510 illustrating the corresponding curves of the potential supplied to terminal 3331 of circuit 333 when potential Vdac is equal to 0.71 V, 0.52 V, 0.30 V and 0 V respectively. otherwise, the curve 502 illustrates the case where the potential Valim is compared with a high threshold of fixed value equal to 5.9 V, the curves 504, 506, 508 and 510 illustrating the cases where the potential Valim is compared with a high threshold of variable value equal to 10.3 V, 13.4 V, 17 V and 21.5 V respectively.

In picture 3 , as long as the potential Valim (curve 500) is not greater than the low threshold UVLO (time t1), the switch 309 is open and the potential Valim is not transmitted to the terminal 3331 of the circuit 333, the potential of this limit then being zero (curves 502, 504, 506, 508 and 510). From time t1, switch 309 closes and the potential on terminal 3331 of circuit 333 (curves 502, 504, 506, 508 and 510) then follows potential Valim.

At a time t2 after time t1, potential Valim becomes greater than 5.9 V, from which it follows that, for the case of curve 502 (static threshold), switch 309 opens and the potential supplied to terminal 3331 of circuit 333 goes to a zero value. After time t2, potential Valim is greater than 5.9 V, from which it follows that, for the case of curve 502, switch 309 remains open and the potential on terminal 3331 remains at a zero value. .

For curves 504, 506, 508 and 510, switch 329 is switched to the closed state between time t1 and time t2, from which it follows that the potential is then compared with a dynamic threshold whose value is fixed by the potential Vdac, according to the negotiated set point value of the potential Valim.

At a time t3 after time t2, potential Valim becomes greater than 10.3 V, from which it follows that, for the case of curve 504, switch 309 opens and the potential supplied to the terminal 3331 of circuit 333 goes to a zero value. After time t3, potential Valim is greater than 10.3 V, from which it follows that, for the case of curve 504, switch 309 remains open and the potential on terminal 3331 remains at a zero value. .

At a time t4 after time t3, potential Valim becomes greater than 13.4 V, from which it follows that, for the case of curve 506, switch 309 opens and the potential supplied to the terminal 3331 of circuit 333 goes to a zero value. After time t4, potential Valim is greater than 13.4 V, from which it follows that, for the case of curve 506, switch 309 remains open and the potential on terminal 3331 remains at a zero value. .

At a time t5 after time t4, potential Valim becomes greater than 15.8 V, from which it follows that, for the case of curve 508, switch 309 opens and the potential supplied to the terminal 3331 of circuit 333 goes to a zero value. After time t5, potential Valim is greater than 15.8 V, from which it follows that, for the case of curve 508, switch 309 remains open and the potential on terminal 3331 remains at a zero value. .

At a time t6 after time t5, potential Valim becomes greater than 21.5 V, from which it follows that, for the case of curve 510, switch 309 opens and the potential supplied to the terminal 3331 of circuit 333 goes to a zero value. After time t6, potential Valim is greater than 21.5 V, from which it follows that, for the case of curve 510, switch 309 remains open and the potential on terminal 3331 remains at a zero value. .

Thus, we see in picture 3 that the switch 309 is indeed switched to the open state as soon as the potential Valim becomes greater than the high threshold, whether the latter is fixed or is variable with a value determined by the negotiated set point value of the potential Valim. The opening of the switch 309 makes it possible to prevent a potential Valim having an overvoltage from being transmitted to the circuit 333 and, more generally, to a load of the device 400 ( figure 1 ) which could be damaged or even destroyed by such an overvoltage.

One could have thought of implementing the comparison of the potential Valim with a threshold of variable value and determined by a negotiated reference value of the potential Valim by using the microcontroller of circuit 331 and an analog-digital converter supplying a binary digital signal representative of a potential value Valim. However, this would require the analog-digital converter to periodically supply a digital signal representative of the potential Valim and that the microcontroller compare, at each period, the output signal of the analog-digital converter to a threshold. This would have resulted in a higher consumption of the resources of the microcontroller of circuit 331 compared to the embodiment described, this consumption of resources would have been all the higher as the period of supply of the digital signal representative of the potential Valim is short.

One could have thought of connecting switch 329 to the input of comparator 323 which is not connected to node 319 of divider bridge 311, and providing a switch between the cathode of diode 327 and this input of the comparator. Thus, this input of the comparator 325 could have been connected either to the cathode of the diode 327, or to the output of the DAC converter. However, the transition from the first phase of operation of the interface 414 (fixed threshold) to the second phase of operation (variable threshold) would then have posed a problem. Indeed, the output of the DAC converter could have been connected to the cathode of diode 327 which could have led to a degradation of diode 327, or could have been floating which could have caused untimely switching of switch 309 .

More broadly, one could have thought of connecting the output of the DAC converter directly instead of diode 327 and planning to control the DAC converter so that it supplies the potential Vdac at a value determined by the value of the high threshold to which is compared the Valim potential. However, the circuit 331 being preferably supplied from the potential available on the terminal 3331, it would have been impossible to control the DAC converter during the first phase when the switch 309 is open, therefore impossible to implement the comparison of the potential Valim at fixed high threshold. Switch 309 would then have remained open, and the DAC converter would have remained without electrical power.

Although the case of an interface 414 has been described above where the power negotiation function is implemented by the circuit 331, provision can be made for the interface to include another circuit configured to implement a such function. This other circuit and the circuit 331 are then preferably linked or connected to each other so that the circuit 331 obtains information representative of the negotiated set point value of the potential Valim, and controls the converter DAC and the switch 329 accordingly.

Various embodiments and variants have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art.

Finally, the practical implementation of the embodiments and variants described is within the abilities of those skilled in the art based on the functional indications given above.

Claims (15)

1. A power supply interface (414) comprising:

   a first switch (309) coupling an input terminal (301) of the interface to an output terminal (305) of the interface;

   a voltage dividing bridge (311) coupling the input terminal (301) to a reference node (313) configured to receive a reference potential (GND), the dividing bridge further comprising a first node (319) and a second node (321) between the input terminal (301) and the reference node (313);

   a comparator (323) having a first input connected to the first node (319) of the dividing bridge and having a second input configured to receive a constant potential (Vth);

   a digital-to-analog converter (DAC);

   a second switch (329) coupling an output of the converter (DAC) to the second node (321) of the dividing bridge (311); and

   a first circuit (331) configured to control the second switch (329) and the converter (DAC),

   wherein a control of the first switch is determined by an output signal (comp_sig) of the comparator (323).
2. The interface of claim 1, wherein the dividing bridge (311) comprises at least a first resistor (R1) coupling the input terminal (301) to the first node (319), at least one second resistor (R2) coupling the first node (319) to the second node (321), and at least one third resistor (R3) coupling the second node (321) to the reference node (313).
3. The interface of claim 1 or 2, wherein the input terminal (301) is configured to receive a first potential (Valim), the output terminal (305) being configured to receive a second potential (Valim').
4. The interface of claim 3, intended to receive the first potential (Valim) of a power source (201) and to deliver the second potential (Valim') to a load.
5. The interface of claim 3 or 4, wherein the first circuit (331) is further configured to negotiate a set point value of the first potential (Valim) and to control the converter (DAC) according to the negotiated set point value.
6. The interface of claim 5, wherein the first circuit (331) is configured to control a turning on of the second switch (329) after the negotiation of said set point value.
7. The interface of any of claims 1 to 6, further comprising a second circuit (325) configured to deliver a signal for controlling the first switch (309) from the output signal (comp_sig) of the comparator.
8. The interface of any of claims 1 to 7, further comprising a third circuit (333) having a first terminal (3331) coupled to the input terminal (301) by the first switch (309) and having a second terminal (3332) coupled to the output terminal (305), the third circuit (333) being configured to deliver, to the second terminal (3332), a potential of the first terminal (3331) in a first operating mode or a third potential in a second operating mode.
9. The interface of claim 8, wherein the first circuit (331) is configured to select an operating mode among the first and second operating modes.
10. The interface of claim 8 or 9, wherein the third circuit (333) comprises a power converter configured to deliver the third potential from the potential of the first terminal (3331) .
11. The interface of any of claims 1 to 10, wherein the first switch (309) is a MOS transistor.
12. The interface of any of claims 1 to 11, wherein the second switch (329) is configured to be off in the absence of a control of the first circuit (331).
13. The interface of any of claims 1 to 12, wherein the second switch (329) is a MOS transistor, preferably normally off.
14. The interface of any of claims 1 to 13, wherein the first circuit (331) comprises, preferably is formed by, a microcontroller.
15. A method of powering a load from a power source (201) comprising the steps of:

    receiving a first potential (Valim) of the source (201);

    detecting with a comparator (323) that the first potential (Valim) is lower than a threshold and conditioning a turning on of a first switch (309) coupling the source (201) to the load to said detection; and

    negotiating, with the source (201), a set point value of the first potential (Valim),

    wherein the threshold is fixed in a first operating mode, and is determined by the negotiated set point value in a second operating mode, the method being implemented by the interface (414) of any of claims 1 to 14.

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